The Preparation Of [⁸⁹Zr]-Df-Bz-NCS-Melan-A Polyclonal Antibody And Imaging Studies In Melanoma

Purpose:To prepare [89Zr]-Df-Bz-NCS-Melan-A polyclonal antibody For human melanoma marker (MART/Melan-A) receptor imaging and evaluate its PET imaging efficacy and distribution in Balb/c nude mice bearing SK-MEL-28 and A375 tumor.Method:Melan-A polyclonal antibody lyophilized powder1.5mg was dissolved in 0.1M sodium bicarbonate solution (NaHCO3) 1ml. After purified and concentrated by PD10 with 0.1M NaHCO3,the purified antibody solution’s PH value was adjusted to 8 with 0.1M NaHCO3.The above purified antibody solution was added DFO(-Df-Bz-NCS-)(concentration is 20mg/ml DMSO) in batches, and 36"C oil bathing for 1h.-Df-Bz-NCS-Melan-A polyclonal antibody was collected and purified by PD10 with 0.15M (PH=7.2) Sodium acetate (NaAc) buffer. Taking an appropriate amount of acetic acid/sodium acetate solution (adjusted PH=7.0) in 3mCi 89Zr sodium oxalate solution, then-Df-Bz-NCS-Melan-A polyclonal antibody was mixed into above reaction system. After reacting at room temperature for 40min, [89Zr]-Df-Bz-NCS-Melan-A polyclonal antibody were collected and purified by PD10 with 0.15M(PH=7.2) Sodium acetate (NaAc) buffer again. [89Zr]-Df-Bz-NCS-Melan-A polyclonal antibody’s RCP and in vitro stability was analyzed by iTLC. PET imaging andbiodistribution were conducted on BALB/c nude mice bearing SK-MEL-28 and A375 tumors.Results:[89Zr]-Df-Bz-NCS-Melan-A polyclonal antibody’s RCY was 54.75% with specific activity of about 1.0mg/mCi and a radiochemical purity of greater than 95%. The imaging agent was stable at room temperature for at least 7 days. SK-MEL-28 melanoma(Melan-A positive) xenograft in the nude mice model was clearly visible with contrast to A375 (Melan-A negative) and background.High uptakes of SK-MEL-28 tumor by quantification of the PET data were detected:8.75±0.91%ID/g、 13.55±0.95%ID/g,15.85±2.55%ID/g at 6 h,24 h and 72 h p.i, respectively. SK-MEL-28 tumor uptake may be blocked by a high dose of Melan-A polyclonal antibody. Biodistribution results, which were consistent with microPET imaging, showed that drug was rapidly cleared in blood and the metabolic uptake in liver was higher than it in kidney. Target background ratio——Tmuor(SK-MEL-28)/Muscle, Tumor/Pancrea, Tumor/liver, was 14.86,8.35,2.02, respectively.Conclusion:The synthetic technology of [89Zr]-Df-Bz-NCS-Melan-A polyclonal antibody is mature. There is a high radiochemical purity, good biodistribution and better targeted imaging, so a preliminary theoretical basis has been provided for [89Zr]-Df-Bz-NCS-Melan-a monoclonal antibody labeling research, Early diagnosis of metastatic melanoma and efficacy of biological target therapy will be aimed by PET imaging in future.